Re: performance issue after upgrade to oracle 18.104.22.168 linux 32 bit.
Date: Wed, 4 Nov 2009 16:56:36 -0800 (PST)
On Nov 4, 2:26 pm, Charles Hooper <hooperc2..._at_yahoo.com> wrote:
> Randolf: regarding the optimizer bug that was fixed in 22.214.171.124 which
> was related to ROWNUM and incorrect cardinality estimates, I was
> unable to force 126.96.36.199 to reproduce the incorrect cardinality
> estimates by changing the OPTIMIZER_FEATURES_ENABLE parameter to match
> a lower release number. So, I guess that some fixes are buried deep
> in the code. I even tried disabling some of the bug fixes without
> success. This seems to imply that changing the
> OPTIMIZER_FEATURES_ENABLE to an older version may not always reproduce
> the old optimizer behavior, which is a bit unfortunate.
Yes, Jonathan blogged about an example of this in "FBI problem" ( http://jonathanlewis.wordpress.com/2007/11/18/fbi-problem/ ) But it's still usually worth a try, if just to narrow possibilities.
Also, just to clearly emphasize to the OP, it is recommended in a lot of places not to set OPTIMIZER_INDEX_COST_ADJ and OPTIMIZER_INDEX_CACHING, at least until testing shows they help - it's likely a mistake to keep the settings from earlier versions. See http://richardfoote.wordpress.com/2009/09/01/optimizer_index_caching-parameter/ for some idea of what to look for.
-- _at_home.com is bogus. http://www.newscientist.com/article/mg20427321.000-clever-fools-why-a-high-iq-doesnt-mean-youre-smart.html?full=trueReceived on Wed Nov 04 2009 - 18:56:36 CST